The present invention relates generally to the field of digital communications, such as the communication of television, multimedia, and/or interactive entertainment and information signals. In particular, the present invention provides methods and apparatus for reconfiguring protocol data for a multiplexed data stream that is reduced to carry fewer services for, e.g., cable-side transmission via a cable television plant. More particularly, the present invention provides methods and apparatus for creating protocol data corresponding to a desired pre-defined combination of multiplexed data stream subgroups contained within an incoming high data rate data stream, such as a high data rate Quadrature Phase Shift Keying (QPSK) modulated multiplexed data stream, when the incoming multiplexed data stream is to be reduced.
When processing high data rate satellite data feeds, it is often necessary to reduce the multiplexed data streams, e.g., for a cable-side multiplex. When reducing a high data rate data stream, some services (such as certain cable television channel services) are dropped. Only a subset of the services in the incoming high data rate data stream may appear in the reduced cable-side output data stream. Therefore, any original protocol data built for the incoming high data rate data stream may no longer be valid for the reduced multiplex.
It would be advantageous to provide methods and apparatus which allow a cable or satellite television headend decoder/transcoder to create and output protocol data which correctly corresponds to the services in the reduced output data stream. It would be further advantageous to provide a high data rate data stream which comprises a predefined set of data stream subgroups, each of the subgroups containing a plurality of services. It would be even further advantageous to provide predefined combinations of the data stream subgroups, each of which predefined combination produces a data stream with a desired reduced data rate. It would be still further advantageous to provide hidden Program Association Tables (PATs), each of which corresponds to a predefined combination of data stream subgroups, as well as hidden protocol data (HPD) base packet identifier (PID) streams corresponding to each hidden PAT, each HPD base PID stream identified by a unique pre-defined PID. The provision of the hidden PATs enable the selection of a hidden PAT corresponding to the desired subgroup combination, for output with the desired subgroup combination as part of the reduced cable-side data stream. The provision of the HPD base PID streams enable the selection of protocol data corresponding to the desired subgroup combination, for output with the desired subgroup combination as part of the reduced cable-side data stream.
The methods and apparatus of the present invention provide the aforesaid and other advantages.